Cross-sectional and longitudinal research of dating and married couples has found robust links among (a) adult attachment, (b) depression and distress, and (c) relationship quality and stability, suggesting that adult attachment may play an important role in both individual and relationship functioning. However, studying already existing, well established relationships does not readily allow us to make causal inferences, nor does it enable us to identify the likely mechanisms of influence. Without such knowledge, it is difficult to develop successful clinical interventions designed to prevent maladaptive interaction patterns to develop in the first place. Thus, what is needed is longitudinal research designed to study the role of adult attachment in the initial relationship formation stage, the time when individuals first develop their "crushes" and relationships are forged. However, these types of studies are virtually non-existent, and no investigation to date has examined the role of adult attachment during this stage of relationship development. In light of the central role individual differences in adult attachment have been shown to play in ongoing relationships, we propose to study their role in a short-term longitudinal study focused on relationship formation among individuals who currently have a crush on someone. Our main goal is to test whether adult attachment differences do indeed play an important causal role in the relationship formation process, and to identify the most likely mechanisms of influence. In particular, the proposed study is designed to (a) test the specific links between adult attachment and systematic differences in cognitive-affective processes when crushes are first developed, (b) examine the longitudinal effects of attachment differences on subsequent relationship functioning and behavioral outcomes as relationships develop, and (c) test specific, mediational processes that help to identify the particular mechanisms of influence, including systematic biases in crush perceptions and judgments of similarity. The proposed study is part of a larger program of research aimed at understanding the pathways through which differences in adult attachment influence cognitive, affective, and behavioral patterns within romantic relationships at all stages of development, including initial attraction, formation, consolidation, and, all too often, dissolution. It is hoped that findings from this research will shed light on the earliest stages of romantic relationship development, thus allowing us to understand the specific ways in which insecure attachment may predispose some individuals to develop intimate relationships that are less likely to succeed. Such knowledge, in turn, is needed to develop effective, targeted, early clinical interventions before maladaptive interaction patterns have formed and relationship quality declined.